Noise reduction device for turbojet nacelle with mobile chevrons, and associated nacelle

Abstract

The invention relates to a turbojet nacelle ( 1 ) and to an aeroacoustic noise reduction device for said nacelle, the nacelle comprising a nozzle ( 10 ) on the downstream end thereof, said nozzle ( 10 ) comprising an inner wall inside which a first flow from the turbojet circulates and an outer wall ( 102 ) outside which a second flow corresponding to the surrounding outside air circulates. The invention also relates to an aeroacoustic noise reduction device ( 20 ) of the turbojet, comprising a plurality of chevrons ( 201 ) arranged on the circumference of the nozzle ( 10 ). The invention is characterized in that the aeroacoustic noise reduction device also comprises a slide ( 202 ) arranged on the circumference of the nozzle in such a way that it can rotate about the axis of the nozzle, each chevron ( 201 ) being connected to the slide ( 202 ) by means of a guiding element ( 204 ) that can move along the slide ( 202 ) during the rotation thereof in order to ensure the displacement of the chevron ( 201 ).

The invention claimed is: 
     
       1. A turbojet nacelle comprising:
 a nozzle on a downstream end thereof, the nozzle comprising an inner wall inside which a first flow from the turbojet circulates and an outer wall outside which a second flow corresponding to surrounding outside air circulates, and 
 an aeroacoustic noise reduction device of the turbojet, comprising a plurality of chevrons arranged on a circumference of the nozzle, 
 wherein the aeroacoustic noise reduction device also comprises a slide arranged on the circumference of the nozzle in such a way that it can rotate about an axis of the nozzle, 
 each chevron being connected to the slide by means of a guiding element that can move along the slide during rotation of the slide in order to ensure displacement of the chevron, the rotation of the slide causing each chevron to rotate around an axis tangent to the circumference of the nozzle. 
 
     
     
       2. The turbojet nacelle according to  claim 1 , wherein the aeroacoustic noise reduction device also comprises a plurality of levers each mounted at one of their ends on the slide via the guiding element, each lever also being fastened at an opposite end to a chevron such that the chevron is capable of being moved in rotation. 
     
     
       3. The turbojet nacelle according to  claim 1 , wherein the slide is a circumferential ring mounted between an inner wall and an outer wall of the nozzle, a radius of which is variable such that each chevron can be moved in rotation around the axis tangent to the circumference of the nozzle. 
     
     
       4. The turbojet nacelle according to  claim 1 , wherein each chevron has a trapezoidal shape. 
     
     
       5. The turbojet nacelle according to  claim 1 , wherein the slide has a wavy or triangular shape depending on the circumference of the nozzle, such that each chevron can be moved in translation between a first position in which the chevron is retracted between the inner and outer walls of the nozzle, and a second position corresponding to an extended position of the chevron. 
     
     
       6. The turbojet nacelle according to  claim 5 , further comprising a plurality of guide rails, arranged between the inner wall and the outer wall of the nozzle, to guide each chevron between the first position and the second position. 
     
     
       7. The turbojet nacelle according to  claim 5 , further comprising a guide rail on either side of each chevron, so as to ensure independent guiding for each chevron. 
     
     
       8. The turbojet nacelle according to  claim 7 , wherein each guide rail corresponds to a female shape, the corresponding chevron has corresponding male lateral shapes. 
     
     
       9. The turbojet nacelle according to  claim 1 , wherein two chevrons arranged successively on the circumference of the nozzle are inclined differently to improve mixing between the first flow and the second flow representing the surrounding outside air. 
     
     
       10. The turbojet nacelle according to  claim 9 , wherein a first chevron is arranged parallel to the inner wall of the nozzle, the following chevron being arranged parallel to the outer wall of the nozzle. 
     
     
       11. The turbojet nacelle according to  claim 1 , further comprising a rack actuated by an electrical motor, or by an electrical or hydraulic jack to ensure rotation of the slide around the circumference of the nozzle. 
     
     
       12. An aeroacoustic noise reduction device of a turbojet, comprising:
 a plurality of chevrons intended to be arranged on the circumference of a turbojet nacelle nozzle, and 
 a slide arranged on a circumference of the nozzle and capable of rotating around an axis of said nozzle, and 
 wherein each chevron being connected to the slide via a guiding element likely to move along the slide during rotation thereof to ensure movement of said chevron, the rotation of the slide causing each chevron to rotate around an axis tangent to the circumference of the nozzle. 
 
     
     
       13. A turbojet nacelle comprising:
 a nozzle on a downstream end thereof, the nozzle comprising an inner wall inside which a first flow from the turbojet circulates and an outer wall outside which a second flow corresponding to surrounding outside air circulates, and 
 an aeroacoustic noise reduction device of the turbojet, comprising a plurality of chevrons arranged on a circumference of the nozzle, 
 wherein the aeroacoustic noise reduction device also comprises a slide arranged on the circumference of the nozzle in such a way that it can rotate about an axis of the nozzle, 
 each chevron being connected to the slide by means of a guiding element that can move along the slide during rotation thereof in order to ensure displacement of the chevron, the rotation of the slide causing each chevron to translate upstream or downstream of the nozzle between a first position in which the chevron is retracted between the inner and outer walls of the nozzle, and a second position corresponding to an extended position of the chevron.